Journal of biomechanics最新文献

{"title":"Machine-based based subtalar pronator and supinator strength training increases rearfoot stability in male runners","authors":"Marco Hagen ,&nbsp;Matthias Lahner ,&nbsp;Nina Lahner","doi":"10.1016/j.jbiomech.2025.112770","DOIUrl":"10.1016/j.jbiomech.2025.112770","url":null,"abstract":"<div><div>Excessive pronation and increased pronation velocity of the foot due to excessive Subtalar Joint (STJ) motion have been discussed as major intrinsic factors for the pathophysiology of overuse running injuries. A possible strategy to reduce these risk factors is the use of the supinator muscles acting eccentrically during the support phase of running. We hypothesised that STJ-specific strength training of the supinator and pronator muscles would be more effective in reducing rearfoot motion compared to traditional plantarflexor and dorsiflexor exercises.</div><div>Twenty healthy male (20–35 years) recreational runners performed machine-based Subtalar Training (ST) with the right foot and machine-based plantar-/ dorsiflexor taining around the Talocrural joint (TT) with the left over a period of ten weeks. STJ muscle strength and shank muscle volume were measured in pre- and posttest. Furthermore, rearfoot motion during overground running (3.3 m/s) was analysed.</div><div>The multifactorial analyses showed significant increases in muscle strength and volume (p &lt; 0.001). Interaction effects (time x group) revealed higher strength increases for ST (p &lt; 0.001) and higher muscle volume increase in the deep supinator muscles (p &lt; 0.05) for ST. The analyses of rearfoot motion showed significant changes after the treatment indicated by a higher inversion angle at touchdown (p &lt; 0.01) and reduced eversion velocity in mid-stance (p &lt; 0.01). Both effects were higher after ST (p &lt; 0.01; time x group interaction).</div><div>Machine-based subtalar-specific strength training represents a potential prevention strategy for male runners to enhance the function of the supinator muscles, to stabilise rearfoot motion during running and, therefore, to reduce lower limb injury risk.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112770"},"PeriodicalIF":2.4,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144116180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abrasion and biomechanics of reconstructed posterior cruciate ligament under different clinical operations","authors":"Xin Jin ,&nbsp;Xihao Huang ,&nbsp;Dangdang Wang ,&nbsp;Zhongmin Jin ,&nbsp;Junyan Li","doi":"10.1016/j.jbiomech.2025.112769","DOIUrl":"10.1016/j.jbiomech.2025.112769","url":null,"abstract":"<div><div>The killer turn and critical corner effects in posterior cruciate ligament (PCL) reconstruction techniques significantly influence graft abrasion and biomechanics. However, the mechanisms of graft failure under physiological loading, considering both killer turn and critical corner effects, have not been thoroughly investigated. 24 porcine knee specimens and 32 grafts were randomly assigned to three different PCL reconstruction techniques. The reconstructed knees underwent 300,000 cycles of gait loading using a knee simulator, followed by load-to-failure tests. Finite element (FE) models of PCL-reconstructed knees were developed to further evaluate the killer turn and critical corner effects on graft biomechanics, focusing on graft-to-bone tunnel contact. Reconstructed grafts using the transtibial technique with anatomic tibial tunnel (ATT: 530.5 N ± 176.3 N) and transtibial technique with a lower tibial tunnel (LTT: 564.3 N ± 249.2 N) demonstrate significantly lower maximum load compared to the tibial inlay technique (TI: 920.7 N ± 201.7 N) (P &lt; 0.05) and the non-operated tissues (1077.8 N ± 127.6 N) (P &lt; 0.001). No significant differences were observed between ATT and LTT grafts (P = 1.000) or between TI grafts and non-operated ones (P = 0.695). FE simulations suggest that the reduced strength of ATT grafts may result from increased contact pressure at the killer turn, while the reduced strength of LTT grafts may be attributed to the heightened windshield wiper effect at the critical corner, induced by the longer graft path. Graft failures in ATT commonly occurred at the killer turn, while LTT and TI grafts failed at the critical corner. The TI technique demonstrates superior abrasion resistance compared to both ATT and LTT techniques.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"188 ","pages":"Article 112769"},"PeriodicalIF":2.4,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144184419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The lacertus fibrosus substantially Alters flexion and supination moment arms: A cadaveric study","authors":"Mark Carl Miller ,&nbsp;Patrick J Schimoler ,&nbsp;Alexander Kharlamov ,&nbsp;Jon Hammerstedt ,&nbsp;Gregory Angelides ,&nbsp;Gonzalo Sumarriva ,&nbsp;Owen Corcoran ,&nbsp;Peter Tang","doi":"10.1016/j.jbiomech.2025.112760","DOIUrl":"10.1016/j.jbiomech.2025.112760","url":null,"abstract":"<div><div>This study evaluated the effect of the lacertus fibrosus on the biceps brachii moment arms to determine the lacertus importance in forearm strength. The work proceeded from the null hypothesis that the lacertus fibrosus has no effect on flexion/extension and supination/pronation.</div><div>Ten fresh-frozen cadaveric specimens were mounted in an elbow simulator to measure tendon excursion, elbow flexion/extension (FE) and forearm pronation/supination (PS) angles. FE moment arms were calculated throughout FE excursion at multiple, constant PS angles and PS moment arms were measured throughout PS excursion at multiple, constant FE angles. Tests included the lacertus intact, the superficial lacertus transected, and the entire lacertus transected along with any connections to surrounding tissue.</div><div>The intact lacertus increased the FE moment arm of the biceps with the elbow in less than 40° flexion and decreased the FE moment arm with the elbow in greater than 80° flexion, where the decrease could exceed 50%, depending on the flexion angle. The intact lacertus decreased the PS supination moment arm at all flexion angles; the intact lacertus even caused the biceps to act as a pronator at full elbow extension.</div><div>The intact lacertus assists in early elbow flexion and the lacertus hinders elbow flexion at greater than 80° flexion. The lacertus hinders the biceps function of supination, especially in a supinated position. Injury of the lacertus without direct biceps tendon damage can be tested best at the ends of the flexion ROM and at higher supination angles. Lacertus syndrome may be more quickly diagnosed with provocative tests that isolate the lacertus function.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112760"},"PeriodicalIF":2.4,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biomechanical mechanisms behind the distal false lumen enlargement after TEVAR for type b aortic dissections: A computational one-way fluid–structure interaction study","authors":"Junheng Li ,&nbsp;Shuaishuai Wang ,&nbsp;Songchen Wang ,&nbsp;Cuiru Sun ,&nbsp;Xiangchen Dai ,&nbsp;Haofei Liu","doi":"10.1016/j.jbiomech.2025.112756","DOIUrl":"10.1016/j.jbiomech.2025.112756","url":null,"abstract":"<div><div>Distal false lumen (FL) expansion is a common complication after thoracic endovascular aortic repair (TEVAR) of type-B aortic dissection (TBAD). FL expansion is likely to cause post dissection aortic aneurysm (PDAA). At present, the biomechanical mechanism leading to the expansion of the FL is not clear, resulting in difficulties in its prevention and treatment. This paper presents a patient-specific one-way fluid–structure interaction (FSI) method for post-TEVAR TBAD patients. This method was then employed to predict the hemodynamic parameters and wall stress in five unstable and five stable patients post-TEVAR. Simulation results were employed to identify the characteristic mechanical parameters for the FL expansion, and to propose a possible mechanism behind FL expansion involving the relationship between the aortic morphology and the characteristic parameters. The pressure difference between false and true lumen, and the average wall stress of FL are recognized as the characteristic parameters for FL expansion, which effectively differentiate the two groups. The threshold value of wall stress between the two groups is about 75 kPa. Abnormally high luminal pressure difference and wall stress in the unstable group were attributed to their anatomical features, such as: enlarged FL, compressed TL, elevated thrombus ratio in FL, and significantly larger tear size. In conclusion, post-TEVAR expansion of the FL is correlated to high luminal pressure difference and elevated FL wall stress, which might be caused by the morphological features of the aorta.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"188 ","pages":"Article 112756"},"PeriodicalIF":2.4,"publicationDate":"2025-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Serial sarcomerogenesis does not contribute to the initial repeated bout effect in skeletal muscle","authors":"Ethan Vlemmix,&nbsp;Avery Hinks,&nbsp;Geoffrey A. Power","doi":"10.1016/j.jbiomech.2025.112767","DOIUrl":"10.1016/j.jbiomech.2025.112767","url":null,"abstract":"<div><div>Neuromuscular function is impaired following an unaccustomed bout of eccentric exercise. However, through the repeated bout effect (RBE), the muscle is protected from impaired neuromuscular function following a subsequent bout of eccentric exercise. It has been speculated that the addition of sarcomeres in series (sarcomerogenesis) contributes to the RBE by reducing mechanical strain on muscle fibers during active lengthening. However, whether sarcomerogenesis actually contributes to the RBE is unknown. We investigated whether a single bout of damaging eccentric exercise induces serial sarcomerogenesis, and if this offers a protective effect on the muscle. Using an in-vivo set up, twenty-four Sprague-Dawley rats performed maximal eccentric contractions of the plantar flexors to impair mechanical function. Thirteen days following the initial eccentric exercise bout, twelve rats were sacrificed, to assess serial sarcomere number (SSN) of the soleus and medial gastrocnemius (MG) via laser diffraction. The remaining twelve rats completed an identical second bout of eccentric exercise to assess the RBE. A single bout caused long lasting impairments in torque production (−3% for 100 Hz; −16 % for 10 Hz; <em>P</em> &lt; 0.05 compared to baseline). Following the repeated bout, there was a protective effect with all torque measures recovering by 2 days post-exercise (<em>P</em> &gt; 0.05 compared to baseline). SSN did not differ between the control and exercised legs for either muscle (<em>P</em> &gt; 0.05). There was a robust RBE following the second bout of eccentric exercise, with no increase in SSN indicating serial sarcomerogenesis is not one of the primary initial mechanisms contributing to the RBE.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112767"},"PeriodicalIF":2.4,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144107123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overground, conventional treadmill, and aquatic treadmill walking joint kinematics differ in typically developing children and adolescents","authors":"Stephanie N. Mace,&nbsp;Joseph W. Harrington,&nbsp;Brian A. Knarr,&nbsp;David C. Kingston","doi":"10.1016/j.jbiomech.2025.112764","DOIUrl":"10.1016/j.jbiomech.2025.112764","url":null,"abstract":"<div><div>Gait training is a common rehabilitation tool using repeated gait cycles to promote motor learning and improve overall walking ability (<span><span>Booth et al., 2018</span></span>, <span><span>Kim and Lee, 2017</span></span> <span><span>Novy et al., 2013</span></span>). The purpose of this study was to quantify differences in peak and time-to-peak ankle plantarflexion, knee flexion, and hip flexion in typically developing children (7 males, 8 females, age 11.3 ± 4.1 years, 1.46 ± 0.18 m, and 44.2 ± 16.8 kg) during overground, conventional treadmill, and aquatic treadmill walking at three walking speeds (slow, normal, and fast). We hypothesized that increasing walking speeds and different walking environments would affect peak and time-to-peak kinematics of the lower limb. Faster speeds significantly increased peak kinematics, with peak plantarflexion increasing from 19.6⁰ during the slow speed condition to 25.7⁰ during the fast speed condition (p &lt; 0.01). The overground environment had the highest peak knee flexion (67.4⁰), a 24.7⁰ increase compared to conventional treadmill and a 34.2⁰ increase compared to the aquatic treadmill (p &lt; 0.01). Time-to-peak kinematics for peak ankle plantarflexion occurred 7.8 % and 9.9 % earlier in the gait cycle when compared to overground (p &lt; 0.01) and conventional treadmill (p &lt; 0.01). Faster speeds also resulted in earlier time-to-peak kinematics compared to slow speeds for ankle plantarflexion (p &lt; 0.01) and hip flexion (p &lt; 0.01). Findings of this study suggest that walking speed and environment significantly influence lower limb kinematics in typically developing children. Therefore, researchers should consider environmental factors when designing and evaluating gait training interventions.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"188 ","pages":"Article 112764"},"PeriodicalIF":2.4,"publicationDate":"2025-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Do gait patterns normalize concurrently with the recovery of foot arches in children with flatfoot? A prospective cohort study","authors":"Yihong Zhao ,&nbsp;Shiyang Yan ,&nbsp;Longbin Zhang ,&nbsp;Bi Shi ,&nbsp;Luming Yang","doi":"10.1016/j.jbiomech.2025.112758","DOIUrl":"10.1016/j.jbiomech.2025.112758","url":null,"abstract":"<div><div>Flexible flatfoot in childhood usually undergoes a spontaneous return to normal. However, during this process, it remains unclear whether the gait pattern will be adjusted concurrently and the mechanism of such adjustment. We investigated the mechanism underlying the change in gait patterns in children after the natural recovery of flat feet through a two-year follow-up study, from the perspectives of plantar loading and gait stability. A total of 15 flatfoot children in the recovery group and 17 typically developed children in the control group were included after extensive sample screening. Three data acquisitions of plantar pressure and Center Of Pressure (COP) were performed every 12 months using a Footscan® pressure plate. Independent t-tests and statistical parametric mapping analysis were used to explore differences between the recovery and control groups at each measurement. At baseline, the recovery group showed higher midfoot loading and a more laterally shifted COP. At the 12-month point, the recovery group manifested a significantly lower load ratio but higher standardized maximum force at the lateral forefoot. At the 24-month point, the recovery group changed to show a considerably higher load ratio under the second metatarsal head, accompanied by a more lateral and posterior COP displacement at the late stance phase. During the recovery of flexible flatfoot morphology in childhood, gait patterns eventually show significant improvement while exhibiting different characteristics at various stages. This study reveals the biomechanical adaptations following the natural recovery of flatfoot in children, contributing to a comprehensive understanding of the impact of pediatric flatfoot.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112758"},"PeriodicalIF":2.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy balance in the pole vault: effect of sex and level of performance","authors":"Julien Frère ,&nbsp;Hugues Thiriot ,&nbsp;Maude Potvin-Gilbert ,&nbsp;Hervé Sanchez ,&nbsp;Sébastien Homo ,&nbsp;Johan Cassirame","doi":"10.1016/j.jbiomech.2025.112765","DOIUrl":"10.1016/j.jbiomech.2025.112765","url":null,"abstract":"<div><div>Performance in pole vaulting is related to the athlete’s mechanical energy when crossing the bar, which corresponds to the sum of the energy during take-off (E_init) and the net energy gain during the pole support phase (E_gain). This study assessed the influence of sex and performance on the trade-off between the E_gain and E_init and aimed to identify the discriminating variables regardless of running speed. Eighty-four athletes were grouped by sex (female, male) and performance standards (inter-regional, national and international). Mechanical energy was computed from successful jumps video recorded in the sagittal plane. Correlations (<em>r</em>) between E_gain and E_init were assessed, and discriminant analysis identified how energy lost during take-off, pole plant timing, pole angle, take-off angle and maximal pole bending differentiated the groups. All correlations were negative (−0.87 &lt; <em>r</em> &lt; -0.41), and only the pole angle and pole plant timing differentiated the groups. The results suggested that each group faced an energy balance between E_gain and E_init, indicating multiple strategies to achieve similar performances. This study highlighted a hierarchy among the variables related to performance, with running speed (E_init) being prioritised, followed by a higher grip favouring E_gain.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112765"},"PeriodicalIF":2.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hemodynamic criteria for intimal tear in Type-B intramural hematoma of aorta based on patient-specific geometry","authors":"Wenyuan Chen ,&nbsp;Weihao Li ,&nbsp;Weikang Xun ,&nbsp;Jing Wang ,&nbsp;Xuemin Zhang ,&nbsp;Zhenchen Hou ,&nbsp;Xiaoming Zhang ,&nbsp;Yantao Yang ,&nbsp;Tao Zhang","doi":"10.1016/j.jbiomech.2025.112739","DOIUrl":"10.1016/j.jbiomech.2025.112739","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study conducts hemodynamic simulations for a total of 20 patients with Type B aortic intramural hematoma (TBIMH) and aims to develop hemodynamic criteria for possible development of intimal tear and indicator for tearing location. The patients are divided into Group A without intimal tear and Group B with progression into tear. The mean oscillatory shear index &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt; is calculated based on the wall shear stress (&lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;W&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt;) distribution. The blood pressure drop along the main aortic vessel is calculated and the high pressure drop time fraction over one cardiac cycle &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is determined, with high pressure drop being defined as the pressure drop larger than half the maximal value. By combining &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; at low heart rates 60bpm and 75bpm, we reveal statistically significant correlation between no progression to tear and both low &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;121&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and low &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;067&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, with a pvalue of &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;7&lt;/mn&gt;&lt;mi&gt;e&lt;/mi&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. We also propose a new parameter, namely the magnitude of tangential pressure gradient at aortic wall &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mo&gt;∇&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; at the time when the pressure drop is maximal during one cardiac cycle. Comparison with CT imaging reveals that nine out of ten patients in Group B develop intimal tear at the location with elevated &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mo&gt;∇&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Therefore, the current study provides a two-step procedure for the hemodynamic diagnosis of TBIMH. First, by combining &lt;span&gt;&lt;math&gt;&lt;mover&gt;&lt;mrow&gt;&lt;mi&gt;O&lt;/mi&gt;&lt;mi&gt;S&lt;/mi&gt;&lt;mi&gt;I&lt;/mi&gt;&lt;/mrow&gt;&lt;mo&gt;¯&lt;/mo&gt;&lt;/mover&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;d&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; those patients with low risk of intimal tear can be excluded. Then, the location of elevated &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mo&gt;∇&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;τ&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mi&gt;p&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; can be adopted as the indicator for possible intimal tear locations.&lt;/","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"187 ","pages":"Article 112739"},"PeriodicalIF":2.4,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144116179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The differential response in fascicle behaviors of the individual plantarflexors to the post-activation potentiation","authors":"Kazuharu Kato ,&nbsp;Sohei Washino ,&nbsp;Patricio A. Pincheira ,&nbsp;Kosuke Hirata ,&nbsp;Yasuhide Yoshitake","doi":"10.1016/j.jbiomech.2025.112759","DOIUrl":"10.1016/j.jbiomech.2025.112759","url":null,"abstract":"<div><div>We aimed to clarify whether post-activation potentiation (PAP) is associated with the amount of fascicle shortening of individual muscles during twitch and whether this relationship depends on muscle fiber composition in humans. Eighteen healthy young adults (four female) participated in this study. Single supramaximal electrical stimulations were applied to the tibial nerve to elicit plantarflexion twitch, involving the medial gastrocnemius (MG) with approximately 50 % Type I fibers and the synergist soleus (SOL) with more than 80 % Type I fibers. The stimuli were delivered before (Pre), immediately after (Post-0 min), 5 min after (Post-5 min), and 10 min after a 6-s maximal voluntary isometric plantarflexion contraction (MVC) and peak torque (PT) during twitch contraction were calculated. The instantaneous fascicle length of each muscle was measured using ultrasound B-mode images acquired at 125 fps during twitch contraction and the amount of fascicle shortening (ΔFL) was calculated. PT was greater after MVC than that at Pre (<em>P</em> &lt; 0.05). The ΔFL of both MG and SOL were greater at Post-0 min and Post-5 min than at Pre (<em>P</em> &lt; 0.05). PT and ΔFL at Post-0 min relative to values at Pre were positively correlated in the MG (r = 0.624, <em>P</em> = 0.006), but not in the SOL. These results suggest that the contribution to PAP of isometric plantarflexion is greater from the MG than that from the SOL, implying a dependence of PAP on muscle fiber composition.</div></div>","PeriodicalId":15168,"journal":{"name":"Journal of biomechanics","volume":"188 ","pages":"Article 112759"},"PeriodicalIF":2.4,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144139062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}